CT331 Solid State Relay - Equivalent & Substitute Parts

Part Overview

The CT331 is a solid-state relay (SSR) manufactured by Coto Technology, designed as a SPST-NO (Single Pole Single Throw - Normally Open) configuration with dual Form A circuits in an 8-DIP package. This component is classified as obsolete, making it necessary to identify equivalent substitute parts for ongoing system support and new designs. The CT331 operates with a 1.37VDC input signal and supports loads up to 350V at 110mA continuous current, making it suitable for low-signal control applications in industrial and commercial equipment.

Substiute Parts

CT331

Coto TechnologyIn Stock: 1519CT331 Datasheet

Current PartRFQ

VOR2142A8

Vishay Semiconductor Opto DivisionIn Stock: 2963VOR2142A8 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the CT331 is determined by strict alignment with the following electrical and mechanical criteria:

Critical Substitution Parameters:

• Circuit configuration: SPST-NO (1 Form A) x 2
• Package footprint: 8-DIP (0.300", 7.62mm)
• Termination style: PC Pin
• Mounting method: Through Hole
• Input voltage compatibility: Within 0.1V tolerance of 1.37VDC
• Load voltage rating: Minimum 350V capability
• Load current capacity: Minimum 110mA

The VOR2142A8 from Vishay Semiconductor Opto Division meets these substitution criteria. It maintains identical package dimensions and circuit topology while providing enhanced electrical specifications. The VOR2142A8 features a higher load voltage rating (400V vs. 350V), increased load current capacity (140mA vs. 110mA), and superior moisture sensitivity characteristics. Input voltage alignment (1.36VDC vs. 1.37VDC) is within acceptable tolerance for direct substitution.

Parameter Comparison

Engineering Selection Recommendations

The VOR2142A8 is the qualified direct substitute for the obsolete CT331. Selection of the VOR2142A8 is supported by:

1. Product Status Advantage: The VOR2142A8 maintains active product status with ongoing manufacturer support, whereas the CT331 is obsolete. This ensures continued availability for production and maintenance applications.

2. Compliance Alignment: Both components maintain ROHS3 compliance. The VOR2142A8 provides superior moisture sensitivity characteristics (MSL 1 vs. MSL 2), offering extended operational reliability in varied environmental conditions.

3. Enhanced Specifications: The VOR2142A8 delivers superior electrical performance with higher load voltage and current ratings, ensuring safe operation in designs that previously utilized the CT331.

4. Pin-Compatible Design: Identical 8-DIP package dimensions and PC Pin termination enable direct board-level substitution without PCB redesign.

Frequently Asked Questions (FAQ)

Q: Can the VOR2142A8 replace the CT331 in existing designs? A: Yes. The VOR2142A8 is pin-compatible and electrically backward-compatible with the CT331. Identical package footprints (8-DIP, 0.300" pitch) and circuit configurations (SPST-NO x 2) enable direct substitution without PCB modifications.

Q: What are the key differences between the CT331 and VOR2142A8? A: The primary differences are load voltage rating (350V vs. 400V), load current capacity (110mA vs. 140mA), on-state resistance (24 Ohms vs. 27 Ohms), and product status (obsolete vs. active). The VOR2142A8 provides enhanced specifications suitable for demanding applications.

Q: Are the input voltage requirements compatible? A: Yes. Input voltage specifications are compatible within acceptable engineering tolerance (1.37VDC vs. 1.36VDC). This minimal 0.01V difference does not impact control signal integrity.

Q: Is the VOR2142A8 suitable for both AC and DC load applications? A: Yes. Both the CT331 and VOR2142A8 support AC and DC output types, maintaining identical load switching capability across voltage polarities.

Q: How does the moisture sensitivity level differ? A: The VOR2142A8 carries MSL 1 (unlimited shelf life), compared to the CT331's MSL 2 (1-year shelf life). This provides superior storage stability and reduced device degradation risk during extended warehousing.

Q: Are both components RoHS-compliant? A: Yes. Both the CT331 and VOR2142A8 maintain ROHS3 compliance, meeting environmental and regulatory requirements for industrial and commercial applications.